Continued high rates of preterm birth and low birthweight, with persistent racial disparities, remain a significant public health concern. Group prenatal care (GPNC), where health care is bundled with education and group support, has demonstrated improved rates of preterm birth. The mechanisms explaining these outcomes are poorly understood. While the causes of poor birth outcomes are complex, stress and anxiety are increasingly recognized as critical contributing factors to poor birth outcomes that also affect child development and maternal functioning postpartum. This proposed dissertation research will investigate the psychosocial outcomes for women participating in GPNC compared to individual prenatal care (IPNC) in a racially diverse, low-income and medically underserved population in South Carolina. This study will employ a convergent parallel mixed-methods design, combining surveys completed by 200 women and qualitative interviews conducted with a subset of 30 women. Using a quasi-experimental, non- equivalent comparison group design, surveys will be conducted at two points during pregnancy and at 6 weeks postpartum to assess the mechanisms and effects of each prenatal care model. Mixed-effects multiple regression will test the hypothesis that GPNC participants demonstrate significantly greater positive psychosocial outcomes, including perceived stress, pregnancy-related anxiety, depressive symptoms, and affect in their third trimester of pregnancy and at 6 weeks postpartum. Path analysis will be employed to test the hypothesis that patient empowerment and coping mechanisms are greater for participants in GPNC, and that these differences explain the relationship between levels of stress and anxiety in the third trimester. Frequent, brief interview with women during pregnancy through six weeks postpartum will build an in-depth understanding of the context that shapes women's use of PNC and the meanings and effects on their and their babies' health that women attribute to PNC. These themes will be compared to the survey results in order to identify potential mechanisms, particularly other coping strategies, not assessed quantitatively. The proposed dissertation research will yield an improved understanding of the mechanisms by which group prenatal care leads to improved birth outcomes, and will lay the groundwork for larger controlled trials. PUBLIC HEALTH RELEVANCE: Prenatal care is one of the most commonly provided health services in the United States, and practices throughout the country are adopting group prenatal care. Evidence supporting the comparative effectiveness of this model of care is needed for health policy makers, providers, and patients. Results will support efforts to improve the quality and effectiveness of prenatal care services in promoting positive birth outcomes, infant development, and maternal well-being.